The present invention relate to a film sticking apparatus having a wet roller for applying an air bubble generation preventive liquid such as water to a base plate so that a film is stuck to the film-stuck surface of the plate by a pressure sticking roller as the liquid remains applied to the surface.
A printed circuit board for an electronic machine such as a computer has wiring made of copper or the like in a prescribed pattern on one or both sides of an electrically insulating base plate. In a process of manufacturing the printed circuit board, a stratified film consisting of a photosensitive resin layer, which is a photoresist layer, and a light-transmissible resin film, which is a protective film for protecting the layer, is first stuck, under heat and pressure, to an electroconductive layer which is a thin copper film provided on the electrically insulating base plate. This heat and pressure sticking is performed by a film sticking apparatus in a mass production manner. As for such apparatuses, various arts were proposed including those disclosed in the Japan Patent Applications (OPI) Nos. 208037/88 and 7344/91 (the term "OPI" as used herein means an "unexamined published application").
FIG. 18 is a schematic side view of a conventional such film sticking apparatus. Since the apparatus is nearly symmetric upward and downward from a conveyance passage for an electrically insulating base plate, FIG. 18 shows only the upper half of the apparatus. In the apparatus, a three-layer stratified film 1 consisting of three layers which are a light-transmissible resin film, a photosensitive resin layer and another light-transmissible resin film is continuously wound on a film supply roller 2 in advance. The film 1 is unwound from the supply roller 2 so that a film separation roller 3 separates the film into the light-transmissible resin film 1A and a two-layer stratified film 1B consisting of the other light-transmissible resin film and the photosensitive resin layer exposed on one side thereof, which is to be stuck to the base plate. The separated stratified film 1B is fed to the surface of a main vacuum suction plate 5 (which is a film feed member) along a tension roller 9. An auxiliary vacuum suction plate 13 and a cutter 14 are provided at the feed passage for the stratified film 1B downstream of the main vacuum suction plate 5 with regard to the direction of the feed of the film. A vacuum suction bar 15 and a pressure sticking roller 16 are provided at the feed passage for the film 1B downstream of the cutter 14. The pressure sticking roller 16 is generally made of a metal tube and a rubber sheet provided on the outer circumferential surface of the tube. The main vacuum suction plate 5 is for tentatively sticking the stratified film 1B to an electroconductive layer on the base plate 6 while holing the film on the suction plate by vacuum suction. The main vacuum suction plate 5 is supported by a support member 7 so as to be movable up and down. The support member 7 can be moved toward and away from the base plate 6 in directions B. The support member 7 is attached with a guide member 8 to the body frame 9 of the apparatus so that the support member can be moved in the directions B while sliding on the guide member. A pair of such support members 7 are provided over and under the conveyance passage for the base plate 6 so that the support members are moved up and down in conjunction with each other through the action of a rack and pinion mechanism by a fist driver not shown in FIG. 14. The mechanism includes racks 7A provided on the support members 7, and a pinion 7B engaged with the racks and supported by the body frame 9 of the apparatus.
The main vacuum suction plate 5 is supported by the support member 7 so that the plate can be moved toward and away from the base plate 6 in directions C, independently of the movement of the support member, by a second driver 11 such as a pneumatic cylinder through the action of a rack and pinion mechanism provided on the support member 7. The mechanism includes a first rack 12A secured to the support member 7, a pinion 12B engaged with the rack so as to be moved up and down along the rack by the driver 11, and a second rack 12C engaged with the pinion so as to be moved up and down in parallel with the former rack. The main vacuum suction plate 5 has a tentatively-sticking downstream end portion 5A in which a heater 5B is provided. To tentatively stick the stratified film 1B to the base plate 6 by the main vacuum suction plate 5, the tentatively-sticking portion 5A thereof is moved to the vicinity of the base plate or into contact therewith as the film remains held on the portion. At that time, the portion 5A is heated by the heater 5B to tentatively stick the film 1B at the leading edge thereof to the base plate under heat and pressure.
The auxiliary vacuum suction plate 13 sucks the stratified film 1B at the leading edge thereof and moves so that the edge of the film is held on the tentatively-sticking downstream end portion 5A of the main vacuum suction plate 5 by suction. For that purpose, the auxiliary vacuum suction plate 13 is moved toward and away from the feed passage for the stratified film 1B in directions D by a driver 13A such as a pneumatic cylinder fastened to the support member 7.
The cutter 14 is opposed to the auxiliary vacuum suction plate 13 across the feed passage for the stratified film 1B in order to cut off the film 1B to a length corresponding to that of the base plate 6.
A pair of pressure sticking rollers 16 are also provided over and under the base plate conveyance passage. The upper and the lower stratified films 1B tentatively stuck to the upper and lower sides of the base plate 6 are pinched thereon under prescribed pressure by the sticking rollers 16 and also heated by them so that the films are completely stuck to the base plate under heat and pressure.
In such film sticking appratus, there is a possibility that a fine air bubble or void space is generated in between the base plate 6 and the film 1B during the sticking thereof to the base plate. This air bubble deteriorates the close adhesion or sticking between the film 1B and the base plate 6. In particular, in case of an insulative base plate on which a wiring pattern having an extremely small wiring line width is formed, this air bubble causes the partial defect of the wiring line, and therefore a defective product is manufactured through the sticking. For that reason, it is necessary to enhance the tightness of the contact of the film 1B and the base plate 6 to prevent the generation of the air bubble, especially in the case that the tightness is likely to fall due to the complicatedness of a wiring pattern. Since applying an air bubble generation preventive liquid such as water to the base plate 6 before the sticking of the film 1B thereto is an effective way of preventing the air bubble from being generated in between the base plate and the film during the sticking, a film sticking apparatus includes wet rollers 18 for applying the liquid to the film-stuck sides of the base plate before the sticking. FIG. 19 shows the state that the conventional wet rollers 18 are provided at the base plate conveyance passage. Shown at 19 and 18A in FIG. 19 are side plates supporting conveyance rollers, and liquid supply blocks, respectively. The wet rollers 18 are in an upper and a lower fixed positions upstream of the pressure sticking rollers 16 so that the upper and lower sides of the base plate 6 come into contact with the wet rollers. For example, the wet roller 18 is that disclosed in the Japan. Patent Application (OPI) No. 7344/91. The wet roller 18 is mainly made of a liquid supply tube, and a coating layer. The tube is a cylindrical body made of a rust-resistant metal such as stainless steel, or a hard plastic, and having a plurality of liquid supply holes. The coating layer is made of a liquid-absorbing porous substance such as sponge, and provided on the outer circumferential surface of the tube. To apply the air bubble generation preventive liquid to the base plate 6 by the wet rollers 18, the liquid is sent into the tubes of the rollers through the ends of the tubes so that the liquid enters into the coating layers of the rollers through the liquid supply holes of the tubes to wet the layers. The upper and lower sides of the base plate 6 come into contact with the coating layers of the wet rollers 18 along with the rotation thereof so that the liquid is applied to the sides. The operation of the apparatus, in which the liquid is applied to the base plate, is herein referred to as wet operation.
There is a kind of a base plate to which such an air bubble generation preventive liquid does not need to be applied. For example, an insulative base plate on which a wiring pattern having not-extremely small wiring line width is to be formed, is that kind. The stratified film is stuck to that kind of base plate by a film sticking apparatus having no such wet roller, or is stuck to the base plate by the former apparatus removed of the wet rollers 18. The operation of the apparatus, in which the liquid is not applied to the base plate, is herein referred to as dry operation.
The wet operation in which the air bubble generation preventive liquid is applied to the base plate, and the dry operation in which the liquid is not applied to the other base plate, sometimes need to be alternately performed. It is conceivable that a film sticking apparatus capable of applying the liquid to the base plate, and a film sticking apparatus not capable of doing so are provided to be alternately used to perform the wet and the dry operations. However, if these different types of apparatuses are provided and alternately used, one of them is always idle and the efficiency of the use of them is therefore low.
If the wet and the dry operations are to be alternately performed by the single conventional apparatus shown in FIG. 18, the wet rollers 18 are left for the wet operation and replaced with dry rollers for the dry operation. However, it takes much time and trouble to attach and detach the wet rollers to and from the apparatus, especially it is very time-consuming to properly position the wet rollers at the base plate conveyance passage. Therefore, often alternately performing the wet and the dry operations by the apparatus is a very heavy work load which is a large impediment to continuously and rapidly operate the apparatus. This is a problem.